Birmingham Platinum Hallmark

[yorkish]

I have a platinum wedding ring clearly hallmarked as Platinum Birmingham 1975
However there is no standard mark.
Does the Orb tell me it is 950 or 999 standard?
Or is the (rather large) 64P stamp indicative of the standard?
If it's not, what is it?
I'm a bit confused with it and would appreciate some help please.
Any thoughts about the SH sponsor?

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[silvermakersmarks]

Modern platinum marking includes a millesimal fineness number but when platinum hallmarking was introduced in 1975 there was a single standard of 950.

Phil

[yorkish]

Thank you, much appreciated.

[dognose]

Maker is very likely to be Samuel Hope Ltd. of Warstone Lane, Birmingham.

Trev.